This invention is directed to oil flow control and more particularly to an oil-flow regulating supply valve for a compressor which is responsive to changes in pressure for changing oil flow volume to the compressor.
In compressors, oil is often supplied for lubrication from a pressurized oil sump. Since the oil is pressure-fed an oil pump is typically not used in a compressor system but oil flow is usually regulated by internal oil metering orifices. In low pressure situations, such as at ambient temperature start up where refrigerant pressures are low, the compressor may operate for a period of time without enough pressure differential to allow the supply of oil at an adequate level. Conventionally, an auxiliary oil pump is used to make up the pressure shortage or a variable restriction is provided on the vapor line downstream of the oil separator and sump to induce a pressure differential. Both solutions can be costly and the provision of a variable restriction can cause an undesirable performance penalty.
Also, during normal operation, it may be desirable to regulate oil flow at extreme operating conditions in a manner other than that provided by internal oil metering orifices.
Therefore, a solution is necessary to provide the benefits of an auxiliary pump or vapor line restriction while eliminating the cost and potential performance penalty. It is also desired to provide a more complex, or programmed, regulation of oil flow than that provided by a simple orifice.
The primary object of this invention is to provide an improved pressure responsive oil flow regulating supply valve for a compressor.
Another object of the present invention is to provide a pressure responsive oil flow regulating supply valve adaptive to multiple pressure situations.
Still another object of the present invention is to provide a pressure responsive oil flow regulating supply valve having a translating spool with varying diameter sections moveable into the oil flow path for regulating oil in response to pressure changes.
And still another object of the present invention is to provide a pressure responsive oil flow regulating supply valve having a translating plunger for exposing one or multiple orifices to oil flow for regulating oil in response to pressure changes.
The foregoing objects and following advantages are achieved by the pressure responsive oil flow regulating supply valve of the present invention which includes an oil supply input; an oil supply output; an oil flow path defined between the input and output; and a valving mechanism located in the oil flow path, the valving mechanism including means for restricting oil flow at predetermined different levels in response to differing pressure conditions.
In one preferred embodiment, the means for restricting preferably comprises a biased spool with multiple portions of differing diameter. Each of the multiple portions has a diameter for restricting flow at one of the predetermined levels in response to varying pressure conditions.
Alternatively, and in another preferred embodiment, the means for restricting comprises a plunger and bore assembly. The plunger translates in the bore formed in the valve assembly housing and the assembly further includes a master orifice and a secondary orifice. The secondary orifice is closed during high pressure for restricted flow and the secondary and master orifices are open during low pressure for increased flow. Additional orifices may also be added to provide additional increments of flow restriction at various pressures.
In another embodiment, the means for restricting further includes means for restricting flow in response to extreme conditions at a first intermediate level between the high level and the low level restrictions.